Background: The pleomorphic clinical presentation makes the diagnosis of desminopathy difficult. We aimed to describe the prevalence, phenotypic expression, and mitochondrial function of individuals with putative disease-causing desmin (DES) variants identified in patients with an unexplained etiology of cardiomyopathy. Methods: A total of 327 Czech patients underwent whole exome sequencing and detailed phenotyping in probands harboring DES variants. Results: Rare, conserved, and possibly pathogenic DES variants were identified in six (1.8%) probands. Two DES variants previously classified as variants of uncertain significance (p.(K43E), p.(S57L)), one novel DES variant (p.(A210D)), and two known pathogenic DES variants (p.(R406W), p.(R454W)) were associated with characteristic desmin-immunoreactive aggregates in myocardial and/or skeletal biopsy samples. The individual with the novel DES variant p.(Q364H) had a decreased myocardial expression of desmin with absent desmin aggregates in myocardial/skeletal muscle biopsy and presented with familial left ventricular non-compaction cardiomyopathy (LVNC), a relatively novel phenotype associated with desminopathy. An assessment of the mitochondrial function in four probands heterozygous for a disease-causing DES variant confirmed a decreased metabolic capacity of mitochondrial respiratory chain complexes in myocardial/skeletal muscle specimens, which was in case of myocardial succinate respiration more profound than in other cardiomyopathies. Conclusions: The presence of desminopathy should also be considered in individuals with LVNC, and in the differential diagnosis of mitochondrial diseases.
Peripartální kardiomyopatie (PPCM) je vzácná, ale potenciálně život ohrožující forma kardiomyopatie. Projevuje se srdečním selháním u žen bez předchozí kardiální anamnézy v časové návaznosti na období kolem porodu, u kterých nelze tento stav vysvětlit jinou příčinou. Incidence PPCM vykazuje velké geografi cké rozdíly, patrně kvůli rozdílům v socioekonomických a genetických faktorech. Jde o velmi vzácné onemocnění, v jehož etiologii, patofyziologii i léčbě existuje stále mnoho neznámých. Podle současných představ jsou podkladem patofyziologie peripartální kardiomyopatie genetické predispozice a dále patologické procesy asociované s těhotenstvím -například preeklampsie, nadměrný oxidační stres a hypersekrece prolaktinu. I když je léčba tohoto onemocnění zatím vzdálena kauzálním postupům, PPCM má v podmínkách vyspělých zdravotnických systémů relativně příznivou prognózu.
Aims The pleomorphic clinical presentation makes the diagnosis of desminopathy difficult. This disease of intermediate filaments causes not only a contractile dysfunction in cardiomyopathy and skeletal myopathy, but also a secondary mitochondrial dysfunction. We aimed to describe prevalence, phenotypic expression and mitochondrial function in desmin mutation carriers identified in a large cohort of patients with unexplained cardiomyopathy. Methods and results A representative cohort of 327 Czech patients with unexplained cardiomyopathy underwent whole exome sequencing. The cohort consisted of cases with familial and sporadic dilated cardiomyopathy (81%), left ventricular noncompaction cardiomyopathy (LVNC) (13%), and less frequently of restrictive (3%) or arrhythmogenic cardiomyopathy (3%). Clinical and laboratory data of desmin mutation carriers were collected. Morphology, desmin expression and mitochondrial function were studied in available myocardial and skeletal muscle specimens. Rare, conserved and possibly pathogenic desmin variants were identified in 6 (1.8%) probands. Two desmin mutations previously classified as variants of uncertain significance (p.K43E, p.S57L), one novel desmin variant (p.A210D) and two known pathogenic desmin mutations (p.R406W, p.R454W) were in affected individuals associated with characteristic pathological desmin aggregates in myocardial and/or skeletal biopsy samples. The individual with the novel desmin variant p.Q364H had decreased myocardial expression of desmin with absent desmin aggregates in myocardial/skeletal biopsy and presented with familial left ventricular non-compaction cardiomyopathy, a novel phenotype of desminopathy. Assessment of mitochondrial function in four carriers of desmin mutations with fresh-frozen skeletal and/or myocardial muscle specimens confirmed decreased metabolic capacity of mitochondrial respiratory chain complexes, which was in case of myocardial succinate respiration more profound than in end-stage heart failure of other etiologies. Genetic testing corrected an inappropriate clinical diagnosis in two probands previously diagnosed with mitochondrial disease and inflammatory cardiomyopathy. During a median follow-up of 56 months, 5 (83%) probands developed end-stage heart failure. Conclusions Desminopathy is a rare cause of cardiomyopathy and/or skeletal muscle myopathy with a pleomorphic clinical presentation and poor prognosis. The presence of desminopathy should be considered also in individuals with left ventricular non-compaction cardiomyopathy, and in the differential diagnosis of mitochondrial diseases and inflammatory cardiomyopathy. Acknowledgement/Funding Research grant of the Ministry of Health, Czech Republic [MZ 15-27682A], No. 00023001 (IKEM, Prague, CZ), the Czech Science Foundation [14-36804G].
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